basie preamp experiments

[Ianm2]

well its built up and running, so time for a preamp shootout.

well, I have had to build it to get some power amps working, its just about done.

I have done it my own way, not the circuit above, the joy of this, with 4 valve sockets, is that you can get a 2 stage phono riaa, a line amp, a cathode follower, and even a passive, in one box.

I have designed 2 circuits for it myself, an srpp, and a parallel grounded cathode, both biased so they won't clip with cd. its looking good, I finish it today and will report on the sound of each.

ecc82s.


I was going to experiment again, but I can't bring myself to deconstruct and rebuild it.

well built, wiring could be tidier, but pretty good, difficult to wire flawlessly this one for some reason.

you can even put 2 power transformers in, I have a spare, and try SS rectification instead of the tube, possibilities are endless, fancy an audio innovations p2 phonostage?, yiou can build that.

this diyhifi stuff is superb.

[Ianm2]

design 1.

last nite I took it around to my friends, and we listened, and both came to the same conclusions, the srpp was better than the paralleled valve.

note this is true for the power supply, and bias currents/operating points I used for my design, it may not be for all, but srpp was far superior. specifically, bass was tighter, midrange richer, and more treble, in every respect, soundstage was big too.

design 2. this morning, undid the parallel pair of 82s, and just used a single, a la sjs, i had good hopes for this one, sadly, seemed very similar to the parallel one, more lean, perhaps cleaner, but less richer, srpp still far more engaging, perhaps a tad too fullsome at times, but i like a soundstage I can eat out of.

listening system.

pioneer pds904 cd player.

own preamp designs running into a switchbox so I can switch between on the fly

300b s.e. monoblocs

speakers of no particular note, home built speaker cables, which are pain in the ass

any old interconnects

next up? anode into cathode follower, a la bottlehead foreplay and eastern electric, already designed the circuit. aha, here it is in front of me, much the same as the others.....pity they are not easy to post here.....

and then? perhaps a grounded grid all good fun.....so far srpp the winner...

I am wondering if that's why the chinese like it, as its bright almost falsely artificial, and you should hear their pop music....

[Ianm2]

design 3., grounded cathode direct coupled into cathode follower.

better than the last 2, bit of extended listening shows something not quite there in the treble, bit sharp, and bass a tad bloated, still the srpp is tighter and fuller in the voice.

srpp still wins...

what next?

ahh, I know, the bottlehead foreplay mk2 uses the same topology but different values, I will try those and see what happens...just a few resistors to alter....

[prince of darkness]

Originally Posted by Ianm2

what next?

What about a μ-follower?

[gilbodavid]

Very interesting shootoutout as i have seduction phono and was thinking of grounded grid pre of some sort as 2nd ever project. what happened next?